System for Testing Ethernet Paths and Links Without Impacting Non-Test Traffic

1. A system for testing Ethernet paths or links without adversely impacting non-test traffic, comprising: at least one pair of Ethernet devices coupled to opposite ends of an Ethernet path or link for transmitting non-test packets on said Ethernet path or link within a predetermined bandwidth limit, at least one test packet generator coupled to said Ethernet path or link for transmitting test packets on said Ethernet path or link to test the transmission characteristics of said Ethernet path or link, said test packet generator including a scheduler that determines when a new test packet is to be created and a packet creator responsive to said scheduler for building new test packets to be transmitted on said Ethernet path or link; a transmit credit block for storing an amount of credits representing a number of bytes that are available to transmit to be within said predetermined bandwidth limit, and decrementing said number of bytes available to transmit each time a test or non-test packet is transmitted via said Ethernet path or link; and a transmit block coupled to said packet creator and said transmit credit block for transmitting said new test packet on said Ethernet path or link when said amount of credits stored in said transmit credit block is sufficient to permit said new test packet to be transmitted without having said non-test packets exceed said predetermined bandwidth limit, wherein the transmit credit block is coupled to the scheduler, the scheduler configured to query the transmit credit block and to send a request to the packet creator to build the test packet responsive to sufficient credits being available from the transmit credit block to transmit the test packet.

2. The system of claim 1 , wherein the transmit block is configured to query the transmit credit block to determine whether sufficient credits are available from the transmit credit block to transmit the test packet.

3. The system of claim 1 , wherein the credits include at least one field from an Ethernet frame.

4. The system of claim 3 , wherein the at least one field is a preamble field of the Ethernet frame.

5. The system of claim 3 , wherein the at least one field is an inter-frame gap of the Ethernet frame.

6. The system of claim 1 , further comprising an Ethernet device, the transmit generator being incorporated into the Ethernet device.

7. The system of claim 1 , wherein the transmit generator includes an Ethernet port, and wherein the transmit generator is connected to the Ethernet link via the Ethernet port.

8. The system of claim 1 , wherein the transmit generator includes at least two Ethernet ports for in-line connection of the transmit generator to the Ethernet link.

9. A system for testing Ethernet paths or links without adversely impacting non-test traffic, comprising: at least one pair of Ethernet devices coupled to opposite ends of an Ethernet path or link for transmitting non-test packets on said Ethernet path or link within a predetermined bandwidth limit, at least one test packet generator coupled to said Ethernet path or link for transmitting test packets on said Ethernet path or link to test the transmission characteristics of said Ethernet path or link, said test packet generator including a scheduler that determines when a new test packet is to be created, and a packet creator responsive to said scheduler for building said new test packet to be transmitted on said Ethernet path or link, a transmit credit block for storing an amount of credits representing a number of bytes that are available to transmit, and decrementing the amount of credits each time a non-test packet or a test packet is transmitted via the Ethernet path or link, and each time a test packet is transmitted via the Ethernet path or link; wherein said scheduler is coupled to said transmit credit block and enables said packet creator to create said new test packet when said amount of credits stored in said transmit credit block is sufficient to transmit said new test packet via a transmit block coupled to said packet creator; and wherein the transmit credit block is coupled to the scheduler, the scheduler configured to query the transmit credit block and to send a request to the packet creator to build the test packet responsive to sufficient credits being available from the transmit credit block to transmit the test packet.